Heavy equipment and machinery frequently require repair and it is generally preferable that such repair be done in the field rather than transporting the machinery or equipment to a suitable repair facility as this reduces the associated time and costs required for repair. One of the most commonly required repairs for large machinery or equipment is the repair of a bore, that is, a circular opening that supports an axle or shaft, for example, and this circular opening becomes damaged or excessively worn due to a variety of different reasons or causes. Alternatively, a bore can be bored out to a slightly larger for a variety of different reasons.
The repair of a damaged or worn bore typically involves rebuilding the interior surface of the bore by the deposition of a metal, typically by a welding or a flame deposition process, and the subsequent boring and machining of the rebuilt or refabricated bore to the a precisely required diameter. These operations are typically performed in the field by means of a portable boring machine which has a boring bar that is inserted into the bore. The boring bar is typically supported on bearings on each side of the bore and may be fitted with a variety of tools for repairing the bore, such as a welding head and a variety of cutting or machining tools.
This arrangement, that is, of a boring bar bearing one or more bore repair tools and supported at each end of the bore by bearings, provides the radial support and rigidity for the tools that is necessary for the accurate reconstruction of a bore, but also presents other problems and shortcomings. For example, and in particular, the accurate reconstruction of a bore requires the periodic measurement of the interior diameter of the bore at various points in the reconstruction process to ensure an accurate rebuilt or refabrication of the bore.
While it is obviously possible to insert any of a number of interior bore measuring devices into a bore, such as interior calipers or an expandible micrometer, it is preferable that the measurements be made without removing the bore bar from the bore as this essentially requires disassembly, or at least dismounting, of a portion of the boring machine, such as the bearings. This, in turn, significantly increases the time required to complete the repair procedure and the probability that errors and inaccuracies will be introduced when reassembling and remounting the bore bar and bearings and/or readjusting the bore bar tool.
The most accurate and cost effective of the previously available bore measurement devices are, therefore, those which are inserted into a tool hole extending across a diameter of the bore bar and which include a mechanism by which the length of a measuring device can be expanded into contact with the interior surface of the bore at a pair of diametrically opposed points. The diameter of the bore can then be determined by withdrawing the bore bar sufficiently from the bore for the measuring device to be removed from the tool hole and measuring the expanded device or reading the diameter from a measurement scale on the device.
However, this type of device is not free of problems because it is necessary to insert an adjustment tool into the bore to expand and lock the measuring device. This requires the adjustment tool to fit between the outside diameter of the bore bar and the inside diameter of the bore, and to be able to operate and function in this space. There is often insufficient space to fit the adjustment tool between the bore bar and the interior of the bore, particularly since it is preferable to use the largest diameter bore bar that will fit into the bore in order to provide the maximum possible radial support and rigidity for the bore bar and tools. This problem may be overcome, for example, by reducing the diameter of the bore bar, but this reduces the radial support and rigidity of the bore bar and tools, thereby increasing the possibility of an error in the diameter or shape of the bore and increasing the time required for the cutting or machining operations. It will also be recognized that this problem cannot be overcome by using a larger diameter bore bar for reconstruction operations and a smaller diameter bore bar for the measurements as this would again require removal of the bore bar and bearings, leading to the same problems as discussed above.
The present invention provides a solution to these and related problems of the prior art.